An air conditioner for cooling immediately according to a prior art is disclosed in, for example, Japanese Patent Application Publication No. H6-211036. This air conditioner performs to cool immediately by using cooling storage medium. However, in a case where the cooling storage medium is used for the air conditioner, there is a limitation to maintain a cooling performance. Specifically, when the air conditioner is not used for a long time, the temperature of the cooling storage medium exceeds over the melting point thereof. Accordingly, a problem that the cooling performance of the air conditioner deteriorates occurs. Therefore, the air conditioner does not perform to cool a compartment of a passenger compartment preliminary before an internal combustion engine of the vehicle starts (i.e., before a passenger gets in the vehicle, that is for example during the vehicle parking). Thus, this air conditioner is only used for air conditioning in a case of an idle stop mode in which the internal combustion engine of the vehicle is temporarily stopped when the vehicle makes a stop for a signal.
Further, another air conditioner for heating immediately according to a prior art is disclosed in, for example, Japanese Patent Application Publication No. 2000-142084 (which corresponds to U.S. Pat. No. 6,166,351). This air conditioner performs to heat immediately by using an electric heater. However, in a case where the electric heater is used for the air conditioner, the heater is not appropriate for the vehicle having a limited power source, since energy consumption of the heater is large. Specifically, an electric generator is stopped when the internal combustion engine of the vehicle is stopped. Therefore, it is difficult for the air conditioner having large electric consumption to control air in a case of preliminary air conditioning mode or idle stop air conditioning mode.
Furthermore, either air conditioner described above does not perform to heat immediately and to cool immediately by using one system or one medium.